Parking meter and rock drill: what they have in common

1. Step 1. Parking meter — evolved from — Vending machine. A payment machine.
2. Step 2. Vending machine — was inspired by — Heron’s aeolipile. Heron described both a holy-water dispenser and the aeolipile; the dispenser is the prototype of the vending machine.
3. Step 3. Heron’s aeolipile — evolved into — Turbine. The aeolipile is the oldest ancestor of the steam turbine.
4. Step 4. Turbine — is part of — Dental drill. An air-driven turbine handpiece.
5. Step 5. Dental drill — uses — Compressed air. Compressed air.
6. Step 6. Compressed air — is used in — Rock drill. Pneumatics.

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